Screwdown device for rolling mill frames and calenders

ABSTRACT

A shrink connection is used between a round pin and a bushing which may be moved relative to each other during screwdown movements of the rolls. The shrink connection permits a rigid and threadless transmission of the rolling force directly to the frame and not through the screwdown device of a rolling mill, said shrink connection may be hydraulically cancelled or released.

United States Patent [15] 3,659,451 Metzger et al. [451 May 2, 1972 s41 SCREWDOWN DEVICE FOR ROLLING [56] References Cited MILL FRAMES AND CALENDERS UNITED STATES PATENTS 72 Inventors: Hans Sle rled Me er St. In bert-Saar; l 1 Fred cerswglgerjsw, g of Gap 2,734,407 2/ 1956 Smith ..72/248 X many 3,286,501 11/1966 Tracy ..72/248 X [73] Assignee: Moeller & Newmann Gmbl-l, lngbert am Primary Examiner -rravis S McGehee h ma Attbmey-John J. Dennemeyer [22] Filed: July 24, 1969 [21] Appl. No.: 844,369 [57] ABS CT A shrink connection is used between a round pin and a bushing which may be moved relative to each other during [30] Foreign Application Priority Data screwdown movements of the rolls. The shrink connection Aug. l, 1968 Germany ..P 17 52 900.9 permits a rigid and threadless transmission of the rolling force directly to the frame and not through the screwdown device of a rolling mill, said shrink connection may be hydraulically [51] Int. B2lb 31/24 cancelled or released. [58] Field of Search 72/248 8 Claims, 2 Drawing Figures I i 75 i 10 i I k 17 *k 12 P'ATENTEMAY 2 I972 SHEET 10F 2 Fig. 7

PATENTEDMAY 2 I972 SHEET 2 UF 2 SCREWDOWN DEVICE FOR ROLLING MILL FRAMES AND CALENDERS The present invention relates to screwdown screwdown device for rolling mill frames and calenders. Rolling mill frames and calenders are usually provided with a screwdown device for adjusting the rolling gap, the device engaging the chocks at both ends of at least one roll of the frame. Screwdown devices which transmit the rolling pressure to the stands of the rolling mill frame are either mechanical or hydraulic devices.

The resilience of the parts of a screwdown device which are affected by the rolling pressure constitutes a considerable proportion of the total resilience of the rolling mill frame and cannot be neglected. In the case of a mechanical screwdown device having compression screws, high resilience can often be explained by the fact that the load is not uniformly supported by all the screw threads at the same time, but that they become fully operative successively under the effect of the deformation caused by the load.

The resilient yield of hydraulic problem devices resides to a large extent in the compressibility of the pressure medium and depends upon the magnitude of the oil column subjected to the pressure fluctuations. From these considerations shut-off valves for controlling the hydraulic screwdown device have previously been disposed in the immediate vicinity of the screwdown cylinders in order to eliminate the efiect of the pressure medium contained in the pipelines; this arrangement obviously means that a shut-off valve must be provided for each screwdown cylinder. In spite of this measure, the height of the oil column in the screwdown cylinders cannot be prevented from increasing as the rolls are screwed down more and more. Thus, the resilience of the screwdown device increases andthe stiffness of the frame decreases in the same proportion as the thickness of the rolled material is reduced. Normally, however, the tolerances for thinner rolled material are closer than for thicker rolled material, a condition which is clearly in opposition to the characteristic of the resilience of known screwdown devices in which the characteristic is dependent upon the rolling gap. This is also true for mechanical screwdown devices having compression screws.

The invention is direction to the problem of avoiding the resilience of parts of a mechanical or hydraulic screwdown device for a rolling mill frame or a calender which transmit the rolling pressure during rolling. This problem is solved according to the invention by the use of hydraulically releasable shrink connections between round pins and bushings which are affected by the forces of the rolling pressure and the relative position of which is changed by screwdown movements.

Such hydraulically releasable shrink connections between round pins and bushings are known for locking hydraulic adjusting drives in a stepless manner (U.S. Pat. No. 3,150,571). In this case, the round pin and the bushing or sleeve are normally secured in their relative position by shrinkage. When oil is introduced at high pressure between the seat surfaces of the shrink connection, the sleeve expands and permits relative displacement between the round pin and the sleeve. The aim of this known locking device is to secure a certain piston position of a hydraulic adjusting drive independently of the sealing tightness of the piston or the shut-off means. Admittedly this advantage is also obtained by the use of the invention in conjunction with a hydraulic screwdown device, however, the use of hydraulically releasable shrink connections according to the invention in the flow path of the rolling pressure force serves the further purpose to transmit the rolling pressure independently of the screwdown device which may be of any construction directly to the frame parts which absorb the rolling pressure and thereby to improve the total resilience of the rolling frame.

For rolling mill frames with closed stands and with chocks guided in the windows thereof, the shrink bushings or sleeves are centrally inserted into the transverse members of the stands with the play required for the hydraulic expansion, and they are attached to the transverse members by means of a collar or flange which transmits the rolling pressure. The

round pins are connected to the chocks in a tension resistant manner so that they are forced to follow the screwdown movement in both directions when the screwdown device is actuated.

In the case of tie rod frames with stand caps the positional height of which is adjustable along the tie-rods and which support the chocks of the upper roll, the round pins are comprised of sleeves which surround the tie-rods and which are clamped between the upper compression nuts of the tie-rods and the lower frame part. The shrink bushings surrounding the sleeve-like round pins are, in this case also, inserted into the stand caps with the play required for the hydraulic expansion, and are attached thereto.

Screwdown movements against the rolling pressure are obviously impossible, just as in the case of rigidly prestressed rolling frames, because the shrink sleeves must be expanded hydraulically for each screwdown movement in order to release the shrink connection. If the rolling frame is to be provided with rolling gap control, or if screwdown movements are to be performed in some other manner under rolling pressure, this can be effected by additional hydraulic pressure cylinder acting upon the chocks of another roll which is not affected by the screwdown device according to the invention. Thus thus, the screwdown device according to the invention serves in for preliminary adjustment of the rolling gap.

Because screwdown against the rolling pressure cannot be effected with the screwdown device according to the invention, as explained, hydraulic double-acting compensating cylinders are sufficient for performing the screwdown movements, and the cylinders may be simultaneously missing the bending cylinders engaging the extended roll necks of an adjustable roll for the purpose of changing the contour of this roll.

Two embodiments of a screwdown device according to the invention are described below by way of example with reference to the accompanying drawings, in which:

FIG. 1 illustrates the upper part of a four-high rolling mill with closed stands, the right-hand stand column being partly broken away and the round pin and sleeve unit being in section, and

FIG. 2 illustrates a tie-rod rolling mill frame with stand caps which are adjustable in positional height for screwdown.

A rolling mill stand 1 illustrated in FIG. 1 receives in its window opening a chock 2 for an upper back-up roll 3. A chock 4 for an upper work roll 5 is guided in a lower recess of the chock 2. An extended roll neck 3a of the back-up roll 3 carries a bearing ring 6 to which are connected two upwardly extending tie-rods 7 by means of which the upper back-up roll 3 is suspended from a conventional balancing means or device; a flat pin 9 and a connecting member 8 which connects the associated tie-rod 7 to the flat pin 9 in a quickly releasable manner, are the only parts of the balancing device visible in FIG. 1.

A flanged bushing or expansible sleeve 10 is inserted into a central opening 11 in a transverse member 1a of the stand 1 and has pronounced play in the central opening 11. The sleeve 10 is attached to the transverse member la by means of the flange 10a. illustrated An engagement member defining engagement surfaces, said member being illustrates as a round pin 1 2 is inserted into the sleeve 10 said sleeve having interior surfaces adapted for movement into abutting relation with the engagement surfaces defined on pin 12 to effect engagement of the surfaces of said pin I 2 and the interior surfaces of the sleeve 1 0 to prevent relative displacement of said sleeve 10 and said pin 12 and hasa lower flange 120. This flange is engaged by a divided ring 13 which can be securely screwed to the chock 2 by means of screws 14, whereby the round pin 12 is connected to the chock 2 in a tension resistant manner, but with a certain amount of play which is visible below the flange 12a and which permits rocking movements of the chock 2 during rolling. Obviously the play is removed prior to rolling by the balancing device and exists then between the upper ring surface of the flange 12a and the detaining ring 13. One half of I 7 and the associated flat pin 9 is omitted for a better clarity of the illustration of the tension resistant connection between the round pin 12 and the chock 2.

The sleeve 10 is connected to the round pin 12 by a shrink connection which can be released by hydraulic expansion of the sleeve 10. The pressure oil needed for this purpose is introduced through a pipe 15 into an axial duct 16 in the round pin 12 and is distributed through a transverse duct 17 to the seating surface between the pin 12 and the sleeve 10.

During rolling, the rolling pressure. is transmitted directly from the chock 2 to the flange 12a of the round pin 12 and further by way of the shrink connection to the shrink sleeve 10 which in turn transmits the rolling pressure by way of its flange 10a to the stand 1. All parts of the balancing device which serves within the scope of the invention as screwdown device are disposed parallel to the shrink connection and thereby free of pressure changes during rolling. Their elastic yield or resilience is thus without effect on the total elastic yield or resilience of the stand.

When the rolling gap is to be widened, the shrink connection is released by feeding pressure oil into the pipe 15; the sleeve 10 can expand because of the play between its outer periphery and the wall of the central opening 11. The chock 2 moves upwardly under the prevailing pressure of the balancing device; its position is fixed by cutting ofi the supply of pressure medium to the balancing cylinders which are not illustrated. Thereupon the pressure employed for the shrink connection between the round pin 12 and the shrink sleeve 10 is reduced, whereby the shrink connection between the two parts is re-established.

When the rolling gap is to be narrowed, the stepless locking connection between the members 10 and 12 is also temporarily released in the manner described above. After removal the pressure from the cylinders of the balancing device the chock 2 together with the upper roll 3 moves downwards under its own weight. Owing to the tension resistant connection between the chock 2 and the round pin 12 the latter is displaced downwardly. Alternatively, however, the cylinders of the balancing device may be constructed in a double acting manner in order to effect adjustment positively in both screwdown directions.

Because the position of the round pin 12 relative to the shrink sleeve 10 determines the magnitude of the adjusted rolling gap independently of the above mentioned play present under its flange 12a, a device not illustrated for indicating the adjusted rolling gap must be connected to the round pin 12.

A four-high frame of tie-rod construction illustrated in FIG. 2 comprises two stands 20 with stand caps 21, from which chocks 23 of upper back-up rolls 24 are suspended in a manner not illustrated in detail. Chocks 25 of an upper working roll 26 are guided in recesses of the chocks 23.

The rolling pressure is absorbed by tie-rods 27 which extend through the lower part of the stands 20 and are stressed by tensioning nuts 28 at the top. The tie-rods 27 are stressed by means of a ring piston 29a of a ring cylinder 29 disposed below the tension nuts-28, in that after lengthening of the tie-rods divided rings are inserted between the tensioning nuts 28 and the ring cylinders 29 and the stressing pressure is released. The stressing pressure is transmitted to the lower parts 20 of the stands by means of an engagement member illustrated as ring sleeves 30 surrounding the tie-rods.

Two expansible shrink sleeves 31 surrounding the ring sleeves 30 are inserted into each stand cap 21 and are provided with flanges 31a by means of which they are supported on the stand cap 21. In this case also, the shrink sleeves 31 have radial play relatively to the stand cap 21, the play being necessary for the hydraulical expansion of the shrink sleeves 31. The pressure oil for expanding the shrink sleeves 31 and for releasing the engagement surfaces of the shrink connection between the shrink sleeves 31 and the ring sleeves 30 is introduced through ducts 32. The region in which the pressure oil becomes effective in order to expand a shrink sleeve is limited by seals 33 and 34.

For the purpose of adjusting the stand cap 21 along the tierods 27 or the ring sleeves 30 surrounding them, two double acting hydraulic adjusting motors 35 are provided which are pivotally connected to eyes 36 of the lower parts of the stands 20, and piston rods 35a of which engage the stand cap 21 at 37. Owing to these double acting adjusting motors 35, the

upper roll set 24, 26 can be moved up and down and thus the rolling gap adjusted thereby after the shrink connection between the shrink bushes 31 and the ring sleeves 30 is released in the same manner as described in connection with FIG. 1.

Alternatively mechanical adjusting devices may be substituted for the adjusting motors 35.

In order that the rolling gap can be altered under rolling pressure in a controlled or uncontrolled manner, hydraulic pressure cylinders 40 with pistons 41 are provided below chocks 39 supporting a lower back up roll 31, the cylinders being located in the lower transverse members 20a of the stands 20.

It is evident that because of the shrink connection between the bushings or sleeves 31 and the ring sleeves 30 the rolling pressure transmitted during rolling to the stand caps 21, is transmitted through the shrink connection directly to the tierods 27 and that the parallel connected hydraulic screwdown devices, that is to say the adjusting motors 35, are shielded from the rolling pressure.

The stressing pressure of the ring pistons 29a prior to the insertion of divided spacer rings, does not only lead to the production of a bias tension in the stressed parts, but also to a compression of the ring sleeves 30. A suitable choice of dimensions of the ring sleeve 30 can attain the result that the compression pressure leads to thickening of the wall of the ring sleeves 30, this being beneficial to the shrink connection. Conversely, however, release of the shrink connection will be assisted when the compression pressure is removed and the ring sleeves 30 lose their load, whereby the wall thickening disappears. When this is the case, it is no longer necessary to expand the shrink sleeves to the degree which would be required if the ring sleeves 30 could not be deformed or thickened by the compression pressure. This difference between the round pin and the bush or sleeve of stress changes necessary for releasing the shrink connection can be advantageous when the shrink connections must be released and re-established again in the short intervals of time such as in reversing frames. The useful working life of the shrink sleeves 31 is increased by the described measure.

A condition of the aforementioned advantages is that the ring pistons 290 are continuously under pressure during rolling. If, however, hollow tie-rods extensible by inner hydraulic pressure are used (German Pat. Nos. 1,050,291 and 1,054,042) the compression of the ring sleeves 30 may be effected by releasing the hydraulic stressing pressure. In this case it is unnecessary to eflect rolling against the hydraulic pressure, but the hydraulic pressure is applied only for releasing the shrink connection in order to remove the load from the ring sleeves 30 by elongating the tie-rods.

What is claimed is:

l. A screw down device for rolling mill frames and calenders comprising:

a. a stand,

b. a chock for carrying a roll,

c. an engagement member defining engagement surfaces,

d. an expansible sleeve about said member having interior surfaces in abutting relation to said engagement surfaces to efi'ect engagement of said surfaces and prevent relative displacement of said sleeve and said member,

e. means for mounting one of said sleeve and said engagement member to said stand and the other of said sleeve and engagement member to said check, and

f. means operatively connected to said sleeve for selectively expanding said sleeve to release said engagement and thereby to allow screwdown movements of said chock.

2. A screw down device as recited in claim 1 wherein the chock is operatively mounted to the engagement member and wherein the stand defines an opening therein for receiving the expansible sleeve, said expansible sleeve being operatively mounted to said stand and said opening being of a sufficient size to permit expansion of the sleeve.

3. A screw down device as recited in claim 1 wherein said means for selectively expanding said sleeve comprises an inlet pipe operatively mounted to the member, said member defining ducts in fluid flow communication with said pipe and the interior surfaces of said sleeve to direct fluid pressure between the surfaces of the member and the sleeve to thereby expand the sleeve and release the member for relative movement within the sleeve.

4. A screw down device as recited in claim 1, further including balancing means operatively connected to said stand and said chock and adapted for selectively adjusting the elevation of the roll carried by said chock.

5. A screw down device as recited in claim 1 wherein said stand is comprised of a pair of spaced stand members each including an upright tie rod, a stand cap and means for mounting the stand cap on respective tie rods so that its elevation is adjustable along the tie rods, said chock being operatively mounted to the respective stand caps, and wherein an engagement member is provided on each of said tie rods, said engage-- ment member being a sleeve surrounding the respective tie rods and wherein a pair of expansible sleeves are provided, each of said expansible sleeves surrounding respective engagement sleeves, said respective stand caps being carried by respective expansible sleeves.

6. A screw down device as recited in claim 5 wherein each of said tie rods is mounted at its upper and lower end portions to respective stand members and the mounting at one of said end portions includes a tensioning nut for tensioning the respective tie rods to the desired degree.

7. A screw down device as recited in claim 6 wherein said engagement sleeves are clampingly engaged by said nuts between a respective nut and a part of the corresponding stand.

8. A screw down device as recited in claim 5 and further including balancing means comprising a pair of hydraulic cylin ders and wherein at each stand a cylinder is connected to one of the stand members and cap stands and the pistons of said cylinders are connected to the other of said stand members and cap stands, said cylinder being activated to selectively move said cap stand relative to the tie rod when the engagement between the expansible sleeve and engagement member is released whereby the elevation of the roll carried by said chock may be selectively varied. 

1. A screw down device for rolling mill frames and calenders comprising: a. a stand, b. a chock for carrying a roll, c. an engagement member defining engagement surfaces, d. an expansible sleeve about said member having interior surfaces in abutting relation to said engagement surfaces to effect engagement of said surfaces and prevent relative displacement of said sleeve and said member, e. means for mounting one of said sleeve and said engagement member to said stand and the other of said sleeve and engagement member to said chock, and f. means operatively connected to said sleeve for selectively expanding said sleeve to release said engagement and thereby to allow screwdown movements of said chock.
 2. A screw down device as recited in claim 1 wherein the chock is operatively mounted to the engagement member and wherein the stand defines an opening therein for receiving the expansible sleeve, said expansible sleeve being operatively mounted to said stand and said opening being of a sufficient size to permit expansion of the sleeve.
 3. A screw down device as recited in claim 1 wherein said means for selectively expanding said sleeve comprises an inlet pipe operatively mounted to the member, said member defining ducts in fluid flow communication with said pipe and the interior surfaces of said sleeve to direct fluid pressure between the surfaces of the member and the sleeve to thereby expand the sleeve and release the member for relative movement within the sleeve.
 4. A screw down device as recited in claim 1, further including balancing means operatively connected to said stand and said chock and adapted for selectively adjusting the elevation of the roll carried by said chock.
 5. A screw down device as recited in claim 1 wherein said stand is comprised of a pair of spaced stand members each including an upright tie rod, a stand cap and means for mounting the stand cap on respective tie rods so that its elevation is adjustable along the tie rods, said chock being operatively mounted to the respective stand caps, and wherein an engagement member is provided on each of said tie rods, said engagement member being a sleeve surrounding the respective tie rods and wherein a pair of expansible sleeves are provided, each of said expansible sleeves surrounding respective engagement sleeves, said respective stand caps being carried by respective expansible sleeves.
 6. A screw down device as recited in claim 5 wherein each of said tie rods is mounted at its upper and lower end portions to respective stand members and the mounting at one of said end portions includes a tensioning nut for tensioning the respective tie rods to the desired degree.
 7. A screw down device as recited in claim 6 wherein said engagement sleeves are clampingly engaged by said nuts between a respective nut and a part of the corresponding stand.
 8. A screw down device as recited in claim 5 and further including balancing means comprising a pair of hydrAulic cylinders and wherein at each stand a cylinder is connected to one of the stand members and cap stands and the pistons of said cylinders are connected to the other of said stand members and cap stands, said cylinder being activated to selectively move said cap stand relative to the tie rod when the engagement between the expansible sleeve and engagement member is released whereby the elevation of the roll carried by said chock may be selectively varied. 